My buddy is going to let me drive is new 545I with the SMG tomorrow. How does this work? do I just go by the revs and push the + button to change gears and the - to gear down. I assume it will not be difficult. I am a little nervous it being someone elses car and snow/slush on the roads.

Whatever you do, for god sakes floor it, and apply the handbrake at every possible turn.